/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.cayte.create2dcode.qrcode.encoder;

import com.cayte.create2dcode.common.BitArray;
import com.cayte.create2dcode.common.WriterException;
import com.cayte.create2dcode.qrcode.decoder.ErrorCorrectionLevel;

/**
 * @author satorux@google.com (Satoru Takabayashi) - creator
 * @author dswitkin@google.com (Daniel Switkin) - ported from C++
 */
public final class MatrixUtil {

	private MatrixUtil() {
		// do nothing
	}

	private static final int[][] POSITION_DETECTION_PATTERN = {
			{ 1, 1, 1, 1, 1, 1, 1 }, { 1, 0, 0, 0, 0, 0, 1 },
			{ 1, 0, 1, 1, 1, 0, 1 }, { 1, 0, 1, 1, 1, 0, 1 },
			{ 1, 0, 1, 1, 1, 0, 1 }, { 1, 0, 0, 0, 0, 0, 1 },
			{ 1, 1, 1, 1, 1, 1, 1 }, };

	private static final int[][] HORIZONTAL_SEPARATION_PATTERN = { { 0, 0, 0,
			0, 0, 0, 0, 0 }, };

	private static final int[][] VERTICAL_SEPARATION_PATTERN = { { 0 }, { 0 },
			{ 0 }, { 0 }, { 0 }, { 0 }, { 0 }, };

	private static final int[][] POSITION_ADJUSTMENT_PATTERN = {
			{ 1, 1, 1, 1, 1 }, { 1, 0, 0, 0, 1 }, { 1, 0, 1, 0, 1 },
			{ 1, 0, 0, 0, 1 }, { 1, 1, 1, 1, 1 }, };

	// From Appendix E. Table 1, JIS0510X:2004 (p 71). The table was
	// double-checked by komatsu.
	private static final int[][] POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE = {
			{ -1, -1, -1, -1, -1, -1, -1 }, // Version 1
			{ 6, 18, -1, -1, -1, -1, -1 }, // Version 2
			{ 6, 22, -1, -1, -1, -1, -1 }, // Version 3
			{ 6, 26, -1, -1, -1, -1, -1 }, // Version 4
			{ 6, 30, -1, -1, -1, -1, -1 }, // Version 5
			{ 6, 34, -1, -1, -1, -1, -1 }, // Version 6
			{ 6, 22, 38, -1, -1, -1, -1 }, // Version 7
			{ 6, 24, 42, -1, -1, -1, -1 }, // Version 8
			{ 6, 26, 46, -1, -1, -1, -1 }, // Version 9
			{ 6, 28, 50, -1, -1, -1, -1 }, // Version 10
			{ 6, 30, 54, -1, -1, -1, -1 }, // Version 11
			{ 6, 32, 58, -1, -1, -1, -1 }, // Version 12
			{ 6, 34, 62, -1, -1, -1, -1 }, // Version 13
			{ 6, 26, 46, 66, -1, -1, -1 }, // Version 14
			{ 6, 26, 48, 70, -1, -1, -1 }, // Version 15
			{ 6, 26, 50, 74, -1, -1, -1 }, // Version 16
			{ 6, 30, 54, 78, -1, -1, -1 }, // Version 17
			{ 6, 30, 56, 82, -1, -1, -1 }, // Version 18
			{ 6, 30, 58, 86, -1, -1, -1 }, // Version 19
			{ 6, 34, 62, 90, -1, -1, -1 }, // Version 20
			{ 6, 28, 50, 72, 94, -1, -1 }, // Version 21
			{ 6, 26, 50, 74, 98, -1, -1 }, // Version 22
			{ 6, 30, 54, 78, 102, -1, -1 }, // Version 23
			{ 6, 28, 54, 80, 106, -1, -1 }, // Version 24
			{ 6, 32, 58, 84, 110, -1, -1 }, // Version 25
			{ 6, 30, 58, 86, 114, -1, -1 }, // Version 26
			{ 6, 34, 62, 90, 118, -1, -1 }, // Version 27
			{ 6, 26, 50, 74, 98, 122, -1 }, // Version 28
			{ 6, 30, 54, 78, 102, 126, -1 }, // Version 29
			{ 6, 26, 52, 78, 104, 130, -1 }, // Version 30
			{ 6, 30, 56, 82, 108, 134, -1 }, // Version 31
			{ 6, 34, 60, 86, 112, 138, -1 }, // Version 32
			{ 6, 30, 58, 86, 114, 142, -1 }, // Version 33
			{ 6, 34, 62, 90, 118, 146, -1 }, // Version 34
			{ 6, 30, 54, 78, 102, 126, 150 }, // Version 35
			{ 6, 24, 50, 76, 102, 128, 154 }, // Version 36
			{ 6, 28, 54, 80, 106, 132, 158 }, // Version 37
			{ 6, 32, 58, 84, 110, 136, 162 }, // Version 38
			{ 6, 26, 54, 82, 110, 138, 166 }, // Version 39
			{ 6, 30, 58, 86, 114, 142, 170 }, // Version 40
	};

	// Type info cells at the left top corner.
	private static final int[][] TYPE_INFO_COORDINATES = { { 8, 0 }, { 8, 1 },
			{ 8, 2 }, { 8, 3 }, { 8, 4 }, { 8, 5 }, { 8, 7 }, { 8, 8 },
			{ 7, 8 }, { 5, 8 }, { 4, 8 }, { 3, 8 }, { 2, 8 }, { 1, 8 },
			{ 0, 8 }, };

	// From Appendix D in JISX0510:2004 (p. 67)
	private static final int VERSION_INFO_POLY = 0x1f25; // 1 1111 0010 0101

	// From Appendix C in JISX0510:2004 (p.65).
	private static final int TYPE_INFO_POLY = 0x537;
	private static final int TYPE_INFO_MASK_PATTERN = 0x5412;

	// Set all cells to -1. -1 means that the cell is empty (not set yet).
	//
	// JAVAPORT: We shouldn't need to do this at all. The code should be
	// rewritten to begin encoding
	// with the ByteMatrix initialized all to zero.
	public static void clearMatrix(ByteMatrix matrix) {
		matrix.clear((byte) -1);
	}

	// Build 2D matrix of QR Code from "dataBits" with "ecLevel", "version" and
	// "getMaskPattern". On
	// success, store the result in "matrix" and return true.
	public static void buildMatrix(BitArray dataBits,
			ErrorCorrectionLevel ecLevel, int version, int maskPattern,
			ByteMatrix matrix) throws WriterException {
		clearMatrix(matrix);
		embedBasicPatterns(version, matrix);
		// Type information appear with any version.
		embedTypeInfo(ecLevel, maskPattern, matrix);
		// Version info appear if version >= 7.
		maybeEmbedVersionInfo(version, matrix);
		// Data should be embedded at end.
		embedDataBits(dataBits, maskPattern, matrix);
	}

	// Embed basic patterns. On success, modify the matrix and return true.
	// The basic patterns are:
	// - Position detection patterns
	// - Timing patterns
	// - Dark dot at the left bottom corner
	// - Position adjustment patterns, if need be
	public static void embedBasicPatterns(int version, ByteMatrix matrix)
			throws WriterException {
		// Let's get started with embedding big squares at corners.
		embedPositionDetectionPatternsAndSeparators(matrix);
		// Then, embed the dark dot at the left bottom corner.
		embedDarkDotAtLeftBottomCorner(matrix);

		// Position adjustment patterns appear if version >= 2.
		maybeEmbedPositionAdjustmentPatterns(version, matrix);
		// Timing patterns should be embedded after position adj. patterns.
		embedTimingPatterns(matrix);
	}

	// Embed type information. On success, modify the matrix.
	public static void embedTypeInfo(ErrorCorrectionLevel ecLevel,
			int maskPattern, ByteMatrix matrix) throws WriterException {
		BitArray typeInfoBits = new BitArray();
		makeTypeInfoBits(ecLevel, maskPattern, typeInfoBits);

		for (int i = 0; i < typeInfoBits.getSize(); ++i) {
			// Place bits in LSB to MSB order. LSB (least significant bit) is
			// the last value in
			// "typeInfoBits".
			boolean bit = typeInfoBits.get(typeInfoBits.getSize() - 1 - i);

			// Type info bits at the left top corner. See 8.9 of JISX0510:2004
			// (p.46).
			int x1 = TYPE_INFO_COORDINATES[i][0];
			int y1 = TYPE_INFO_COORDINATES[i][1];
			matrix.set(x1, y1, bit);

			if (i < 8) {
				// Right top corner.
				int x2 = matrix.getWidth() - i - 1;
				int y2 = 8;
				matrix.set(x2, y2, bit);
			} else {
				// Left bottom corner.
				int x2 = 8;
				int y2 = matrix.getHeight() - 7 + (i - 8);
				matrix.set(x2, y2, bit);
			}
		}
	}

	// Embed version information if need be. On success, modify the matrix and
	// return true.
	// See 8.10 of JISX0510:2004 (p.47) for how to embed version information.
	public static void maybeEmbedVersionInfo(int version, ByteMatrix matrix)
			throws WriterException {
		if (version < 7) { // Version info is necessary if version >= 7.
			return; // Don't need version info.
		}
		BitArray versionInfoBits = new BitArray();
		makeVersionInfoBits(version, versionInfoBits);

		int bitIndex = 6 * 3 - 1; // It will decrease from 17 to 0.
		for (int i = 0; i < 6; ++i) {
			for (int j = 0; j < 3; ++j) {
				// Place bits in LSB (least significant bit) to MSB order.
				boolean bit = versionInfoBits.get(bitIndex);
				bitIndex--;
				// Left bottom corner.
				matrix.set(i, matrix.getHeight() - 11 + j, bit);
				// Right bottom corner.
				matrix.set(matrix.getHeight() - 11 + j, i, bit);
			}
		}
	}

	// Embed "dataBits" using "getMaskPattern". On success, modify the matrix
	// and return true.
	// For debugging purposes, it skips masking process if "getMaskPattern" is
	// -1.
	// See 8.7 of JISX0510:2004 (p.38) for how to embed data bits.
	public static void embedDataBits(BitArray dataBits, int maskPattern,
			ByteMatrix matrix) throws WriterException {
		int bitIndex = 0;
		int direction = -1;
		// Start from the right bottom cell.
		int x = matrix.getWidth() - 1;
		int y = matrix.getHeight() - 1;
		while (x > 0) {
			// Skip the vertical timing pattern.
			if (x == 6) {
				x -= 1;
			}
			while (y >= 0 && y < matrix.getHeight()) {
				for (int i = 0; i < 2; ++i) {
					int xx = x - i;
					// Skip the cell if it's not empty.
					if (!isEmpty(matrix.get(xx, y))) {
						continue;
					}
					boolean bit;
					if (bitIndex < dataBits.getSize()) {
						bit = dataBits.get(bitIndex);
						++bitIndex;
					} else {
						// Padding bit. If there is no bit left, we'll fill the
						// left cells with 0, as described
						// in 8.4.9 of JISX0510:2004 (p. 24).
						bit = false;
					}

					// Skip masking if mask_pattern is -1.
					if (maskPattern != -1) {
						if (MaskUtil.getDataMaskBit(maskPattern, xx, y)) {
							bit = !bit;
						}
					}
					matrix.set(xx, y, bit);
				}
				y += direction;
			}
			direction = -direction; // Reverse the direction.
			y += direction;
			x -= 2; // Move to the left.
		}
		// All bits should be consumed.
		if (bitIndex != dataBits.getSize()) {
			throw new WriterException("Not all bits consumed: " + bitIndex
					+ '/' + dataBits.getSize());
		}
	}

	// Return the position of the most significant bit set (to one) in the
	// "value". The most
	// significant bit is position 32. If there is no bit set, return 0.
	// Examples:
	// - findMSBSet(0) => 0
	// - findMSBSet(1) => 1
	// - findMSBSet(255) => 8
	public static int findMSBSet(int value) {
		int numDigits = 0;
		while (value != 0) {
			value >>>= 1;
			++numDigits;
		}
		return numDigits;
	}

	// Calculate BCH (Bose-Chaudhuri-Hocquenghem) code for "value" using
	// polynomial "poly". The BCH
	// code is used for encoding type information and version information.
	// Example: Calculation of version information of 7.
	// f(x) is created from 7.
	// - 7 = 000111 in 6 bits
	// - f(x) = x^2 + x^1 + x^0
	// g(x) is given by the standard (p. 67)
	// - g(x) = x^12 + x^11 + x^10 + x^9 + x^8 + x^5 + x^2 + 1
	// Multiply f(x) by x^(18 - 6)
	// - f'(x) = f(x) * x^(18 - 6)
	// - f'(x) = x^14 + x^13 + x^12
	// Calculate the remainder of f'(x) / g(x)
	// x^2
	// __________________________________________________
	// g(x) )x^14 + x^13 + x^12
	// x^14 + x^13 + x^12 + x^11 + x^10 + x^7 + x^4 + x^2
	// --------------------------------------------------
	// x^11 + x^10 + x^7 + x^4 + x^2
	//
	// The remainder is x^11 + x^10 + x^7 + x^4 + x^2
	// Encode it in binary: 110010010100
	// The return value is 0xc94 (1100 1001 0100)
	//
	// Since all coefficients in the polynomials are 1 or 0, we can do the
	// calculation by bit
	// operations. We don't care if cofficients are positive or negative.
	public static int calculateBCHCode(int value, int poly) {
		// If poly is "1 1111 0010 0101" (version info poly), msbSetInPoly is
		// 13. We'll subtract 1
		// from 13 to make it 12.
		int msbSetInPoly = findMSBSet(poly);
		value <<= msbSetInPoly - 1;
		// Do the division business using exclusive-or operations.
		while (findMSBSet(value) >= msbSetInPoly) {
			value ^= poly << (findMSBSet(value) - msbSetInPoly);
		}
		// Now the "value" is the remainder (i.e. the BCH code)
		return value;
	}

	// Make bit vector of type information. On success, store the result in
	// "bits" and return true.
	// Encode error correction level and mask pattern. See 8.9 of
	// JISX0510:2004 (p.45) for details.
	public static void makeTypeInfoBits(ErrorCorrectionLevel ecLevel,
			int maskPattern, BitArray bits) throws WriterException {
		if (!QRCode.isValidMaskPattern(maskPattern)) {
			throw new WriterException("Invalid mask pattern");
		}
		int typeInfo = (ecLevel.getBits() << 3) | maskPattern;
		bits.appendBits(typeInfo, 5);

		int bchCode = calculateBCHCode(typeInfo, TYPE_INFO_POLY);
		bits.appendBits(bchCode, 10);

		BitArray maskBits = new BitArray();
		maskBits.appendBits(TYPE_INFO_MASK_PATTERN, 15);
		bits.xor(maskBits);

		if (bits.getSize() != 15) { // Just in case.
			throw new WriterException("should not happen but we got: "
					+ bits.getSize());
		}
	}

	// Make bit vector of version information. On success, store the result in
	// "bits" and return true.
	// See 8.10 of JISX0510:2004 (p.45) for details.
	public static void makeVersionInfoBits(int version, BitArray bits)
			throws WriterException {
		bits.appendBits(version, 6);
		int bchCode = calculateBCHCode(version, VERSION_INFO_POLY);
		bits.appendBits(bchCode, 12);

		if (bits.getSize() != 18) { // Just in case.
			throw new WriterException("should not happen but we got: "
					+ bits.getSize());
		}
	}

	// Check if "value" is empty.
	private static boolean isEmpty(int value) {
		return value == -1;
	}

	// Check if "value" is valid.
	private static boolean isValidValue(int value) {
		return (value == -1 || // Empty.
				value == 0 || // Light (white).
		value == 1); // Dark (black).
	}

	private static void embedTimingPatterns(ByteMatrix matrix)
			throws WriterException {
		// -8 is for skipping position detection patterns (size 7), and two
		// horizontal/vertical
		// separation patterns (size 1). Thus, 8 = 7 + 1.
		for (int i = 8; i < matrix.getWidth() - 8; ++i) {
			int bit = (i + 1) % 2;
			// Horizontal line.
			if (!isValidValue(matrix.get(i, 6))) {
				throw new WriterException();
			}
			if (isEmpty(matrix.get(i, 6))) {
				matrix.set(i, 6, bit);
			}
			// Vertical line.
			if (!isValidValue(matrix.get(6, i))) {
				throw new WriterException();
			}
			if (isEmpty(matrix.get(6, i))) {
				matrix.set(6, i, bit);
			}
		}
	}

	// Embed the lonely dark dot at left bottom corner. JISX0510:2004 (p.46)
	private static void embedDarkDotAtLeftBottomCorner(ByteMatrix matrix)
			throws WriterException {
		if (matrix.get(8, matrix.getHeight() - 8) == 0) {
			throw new WriterException();
		}
		matrix.set(8, matrix.getHeight() - 8, 1);
	}

	private static void embedHorizontalSeparationPattern(int xStart,
			int yStart, ByteMatrix matrix) throws WriterException {
		// We know the width and height.
		if (HORIZONTAL_SEPARATION_PATTERN[0].length != 8
				|| HORIZONTAL_SEPARATION_PATTERN.length != 1) {
			throw new WriterException("Bad horizontal separation pattern");
		}
		for (int x = 0; x < 8; ++x) {
			if (!isEmpty(matrix.get(xStart + x, yStart))) {
				throw new WriterException();
			}
			matrix.set(xStart + x, yStart, HORIZONTAL_SEPARATION_PATTERN[0][x]);
		}
	}

	private static void embedVerticalSeparationPattern(int xStart, int yStart,
			ByteMatrix matrix) throws WriterException {
		// We know the width and height.
		if (VERTICAL_SEPARATION_PATTERN[0].length != 1
				|| VERTICAL_SEPARATION_PATTERN.length != 7) {
			throw new WriterException("Bad vertical separation pattern");
		}
		for (int y = 0; y < 7; ++y) {
			if (!isEmpty(matrix.get(xStart, yStart + y))) {
				throw new WriterException();
			}
			matrix.set(xStart, yStart + y, VERTICAL_SEPARATION_PATTERN[y][0]);
		}
	}

	// Note that we cannot unify the function with
	// embedPositionDetectionPattern() despite they are
	// almost identical, since we cannot write a function that takes 2D arrays
	// in different sizes in
	// C/C++. We should live with the fact.
	private static void embedPositionAdjustmentPattern(int xStart, int yStart,
			ByteMatrix matrix) throws WriterException {
		// We know the width and height.
		if (POSITION_ADJUSTMENT_PATTERN[0].length != 5
				|| POSITION_ADJUSTMENT_PATTERN.length != 5) {
			throw new WriterException("Bad position adjustment");
		}
		for (int y = 0; y < 5; ++y) {
			for (int x = 0; x < 5; ++x) {
				if (!isEmpty(matrix.get(xStart + x, yStart + y))) {
					throw new WriterException();
				}
				matrix.set(xStart + x, yStart + y,
						POSITION_ADJUSTMENT_PATTERN[y][x]);
			}
		}
	}

	private static void embedPositionDetectionPattern(int xStart, int yStart,
			ByteMatrix matrix) throws WriterException {
		// We know the width and height.
		if (POSITION_DETECTION_PATTERN[0].length != 7
				|| POSITION_DETECTION_PATTERN.length != 7) {
			throw new WriterException("Bad position detection pattern");
		}
		for (int y = 0; y < 7; ++y) {
			for (int x = 0; x < 7; ++x) {
				if (!isEmpty(matrix.get(xStart + x, yStart + y))) {
					throw new WriterException();
				}
				matrix.set(xStart + x, yStart + y,
						POSITION_DETECTION_PATTERN[y][x]);
			}
		}
	}

	// Embed position detection patterns and surrounding vertical/horizontal
	// separators.
	private static void embedPositionDetectionPatternsAndSeparators(
			ByteMatrix matrix) throws WriterException {
		// Embed three big squares at corners.
		int pdpWidth = POSITION_DETECTION_PATTERN[0].length;
		// Left top corner.
		embedPositionDetectionPattern(0, 0, matrix);
		// Right top corner.
		embedPositionDetectionPattern(matrix.getWidth() - pdpWidth, 0, matrix);
		// Left bottom corner.
		embedPositionDetectionPattern(0, matrix.getWidth() - pdpWidth, matrix);

		// Embed horizontal separation patterns around the squares.
		int hspWidth = HORIZONTAL_SEPARATION_PATTERN[0].length;
		// Left top corner.
		embedHorizontalSeparationPattern(0, hspWidth - 1, matrix);
		// Right top corner.
		embedHorizontalSeparationPattern(matrix.getWidth() - hspWidth,
				hspWidth - 1, matrix);
		// Left bottom corner.
		embedHorizontalSeparationPattern(0, matrix.getWidth() - hspWidth,
				matrix);

		// Embed vertical separation patterns around the squares.
		int vspSize = VERTICAL_SEPARATION_PATTERN.length;
		// Left top corner.
		embedVerticalSeparationPattern(vspSize, 0, matrix);
		// Right top corner.
		embedVerticalSeparationPattern(matrix.getHeight() - vspSize - 1, 0,
				matrix);
		// Left bottom corner.
		embedVerticalSeparationPattern(vspSize, matrix.getHeight() - vspSize,
				matrix);
	}

	// Embed position adjustment patterns if need be.
	private static void maybeEmbedPositionAdjustmentPatterns(int version,
			ByteMatrix matrix) throws WriterException {
		if (version < 2) { // The patterns appear if version >= 2
			return;
		}
		int index = version - 1;
		int[] coordinates = POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE[index];
		int numCoordinates = POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE[index].length;
		for (int i = 0; i < numCoordinates; ++i) {
			for (int j = 0; j < numCoordinates; ++j) {
				int y = coordinates[i];
				int x = coordinates[j];
				if (x == -1 || y == -1) {
					continue;
				}
				// If the cell is unset, we embed the position adjustment
				// pattern here.
				if (isEmpty(matrix.get(x, y))) {
					// -2 is necessary since the x/y coordinates point to the
					// center of the pattern, not the
					// left top corner.
					embedPositionAdjustmentPattern(x - 2, y - 2, matrix);
				}
			}
		}
	}

}
